The present invention relates to a drive and tensioning station of a chain scraper conveyor for mining operations with a machine frame base having side cheeks and a conveyor base, connected to a line of pans of the chain scraper conveyor, with a tensioning frame head which can be moved in the direction of the line of pans, in whose side cheek plates can be mounted the chain drum for the scraper chain, and with a tensioning drive having at least one tensioning cylinder to move the tensioning frame head relative to the machine frame base.
A drive and tensioning station of this construction is proposed in DE 39 23 320 A1. The previously proposed drive station has side cheeks, which are joined via cross beams to a rigid machine frame. The side cheeks extend essentially over the entire length of the drive station and have window-like cut-outs, in which bearing cheek plates are taken onto which the chain drum for the scraper chain is mounted. In order to provide a clean run of the tensioning cradle retained in the bearing cheek plates in the machine frame, guide rails are arranged at a distance from each other above and below the cut-out, which have hooks protruding outwards and upwards and downwards. The bearing cheek plates taken into the cut-out, which are penetrated by the chain drum shaft, are firmly joined with flange plates, onto which the conveyor drive can be flanged. The flange plates have claw shaped guide attachments above and below complementing the guide rails, which engage the guide rails in the manner of hooks. The combination of bearing cheeks and flange plates provided with guide attachments caters for a positive guidance of the tensioning frame head in the tensioning direction, or the opposite direction from the conveyor chain, the construction is however overall relatively expensive. In order to obtain a large tensioning path for the scraper chain, the scraper chain tensioning cylinders are supported at one end on a cross beam of the tensioning cradle and at their other ends on a connection pan, which in a well known manner, forms the transition between the drive station and the line of pans. The tensioning cylinders thus overlap the abutment or impacting position between the drive station and the connection pan. The tensioning cylinders of the tensioning drive for the scraper chain lie here between the side cheeks of the machine frame of the drive station.
It is an aim of the present invention to produce a drive and tensioning station with a simplified construction, which can be disassembled comparatively quickly and whose parts which are liable to wear can be exchanged in a simple manner.
Accordingly the present invention is directed to a drive and tensioning station as set out in the opening paragraph of the present specification, in which the tensioning frame head has a box-like drawer extending out over the side cheek plates toward the pan connection side, which is guided in a type of drawer guide on the machine frame base and in which on the tensioning frame head a top run pan forming a drag plate in the top run and/or a bottom run box forming a drag base in the bottom run is/are removably fastened.
In comparison with the prior art the drawer like guidance of the tensioning frame head within the stationary machine frame base ensures a significant saving of material and weight, since side cheeks which extend over the entire length of the drive station can be dispensed with. The depth of the machine frame base and the length of the drawer together with the lifting height determine the possible tensioning path. For the drawer guidance it can especially be exploited that in drive and tensioning stations a relatively large height difference exists between the top run and the bottom run, in order to guide the scraper and the scraper chain essentially tangential to the chain sprocket of the chain drum shaft. This height difference offers sufficient space for a powerful, stable and secure guidance of the tensioning frame head in the machine frame base. The drawer guide lies between the side cheeks of the machine frame base and is therefore largely protected against the ingress of conveyed material. Since the box-like guide drawer is positioned behind the side cheek plates of the tensioning frame head in the tensioning direction, it is possible at the same time to fasten a wear-prone drag plate or a wear-pone drag base removably to the side cheek plates or to the tensioning frame head in a relatively simple manner, whereby the connecting positions between the drag plate or base and the tensioning frame head are easily accessible by pushing out the tensioning frame head by a few centimeters, so that the top run pan and the bottom run box can possibly be quickly exchanged if too greatly worn.
The exchange of the top run pan and of the bottom run box is simple if the side cheek plates of the tensioning frame head are provided in each case with at least two connecting eyes on their front sides on the pan connection side, onto which the top run pan and the bottom run box are removeably fastened by means of push-in or screw pins. Preferably the pins are secured by means of substantially U-shaped push-in staples on or in the connecting eyes.
Advantageously the drawer guide includes several exchangeably fastened U-shaped angle irons fastened in the side cheeks of the machine frame base, whereby the inner surfaces of the angle irons form the guides for sliding the drawer and the upper surfaces of the webs of the angle irons support for the top run pan. By the use of several U-shaped angle irons with comparatively small abutment zones for the drawer and the upper drag plate the frictional forces between the parts which move against each other and are guided in each other can be reduced. Possibly again the feasibility is offered of exchanging the angle irons in the event of too great wear on them. Furthermore the drawer guide can have a closed upper cover forming the conveyor base and a lower cover preferably provided with openings for passage of fine grain material.
Especially the top run pan has a pan base and side profiles, on whose inner profile surfaces the scrapers of the chain scraper are guided, so that the top run pan caters for an extension of the top run and the material conveyed with the chain scraper conveyor, for instance coal, is taken independently of the tension setting, in a channel enclosed at the sides and below, up to the chain drum shaft. Advantageously the side cheeks of the machine frame base are provided with upper horizontal longitudinal rails, which form an upper guide for the top run pan and its side profiles. With these measures horizontal guidance is assured for the top run pan in the top run and vertical tilting of the top run pan is prevented, although the top run pan itself is only joined at, for instance, two fastening positions to the tensioning frame head. In a preferred embodiment the conveyor base of the machine frame base is provided on the pan connection side with a tongue-shaped cover plate, cut to size, and the top run pan has a corresponding tongue-shaped cut-out, whereby the edges of the plate and the cut-out are provided with a ramp-like incline. The incline on the edges of the plate and the cut-out come into effect when the tensioning frame head is retracted into the machine frame base, since the conveyed material, which when the top run pan is completely extended, collects in zones which lie deeper than the actual conveyor base level, can be forced upwards by the ramp effect of the inclines, whilst the yielding movement of the tensioning frame head is not hindered by conveyed material such as coal dust.
Preferably the bottom run box has an upper covering plate provided with openings for the passage of fine grain material. It is understood that then the openings in the upper covering plate of the bottom run box must work together with the openings in the lower covering plate of the drawer-like guide, so that any conveyed material which may inadvertently be taken into the drawer guide can escape out of the hollow drawer guide. Especially the openings in the cover plate have a greater extension in the direction of movement than the openings in the lower cover of the drawer guide, or vice versa, so that in no position in the movement of the tensioning frame head relative to the machine frame base are the openings fully closed. It is expedient here also if the bottom run box has a tongue shaped cut-out on the pan connecting side, whose edges preferably are provided with an incline. In a preferred embodiment the tongue-shaped cut-outs in the top run pan and/or in the bottom run box extend over more than the maximum tensioning distance, so that the scrapers taken in the top run and in the bottom run and moving along do not run over the inclines on the edges of the cutouts, and can therefore run evenly through the drive station.
For twist-free movement of the tensioning frame head relative to the machine frame base, at least one tensioning cylinder is linked on each side to the side cheek plate of the machine frame base at one end and at the other end to the side cheek plate of the tensioning frame head, whereby two tensioning cylinders are arranged preferably at the same height level as the drawer guide, or four tensioning cylinders are arranged symmetrically to the drawer guide. Preferably flange plates are arranged outside on the side cheek plates, possibly with the interposition of intermediate plates onto which a drive set for the conveyor can be fastened, whereby the connecting plates for fastening the tensioning cylinders to the tensioning frame head are supported on the flange plate, on the side cheek plates and possibly on the intermediate plates.